Expandable implantable devices are often used for opening and closing passageways or orifices within the vascular, urinary, or gastrointestinal (GI) systems. Examples include vascular and GI stents for opening occlusions, left atrial appendage (LAA) and patent foramen ovale (PFO) occluding devices, and others. Such implantable devices typically consist of a scaffold that is introduced in a collapsed state and is expanded to a desired configuration at a target organ.
U.S. Provisional Patent Application 61/746,423, filed Dec. 27, 2012, to Yodfat and Shinar, assigned to Javelin Medical Ltd., discloses expandable devices and a method for implanting the devices within the body. Some of the embodiments of that disclosure are directed to devices made of super-elastic metal (e.g., nitinol) configured into a monofilament which is spatially bent and/or twisted (e.g., upon delivery). Such devices have two operating states—a contracted state (undeployed) and an expanded state (deployed). The devices may be implanted using a delivery system comprising (for example) a rigid needle having a preferred diameter of <1 mm (3 French, 0.04″) and a sharp distal end. The devices may be preassembled within the needle in their stretched, substantially-linear, undeployed state and positioned at the needle's distal end. A pusher, in the form of an elongated rod, may also be preassembled within the needle, extending from proximally to the proximal end of the needle to the proximal end of the device. The implantation of the device may be performed by piercing the skin and underlying tissues and advancing the needle to the target organ under ultrasound guidance. At the desired location, the device may be exteriorized by retracting the needle with respect to the patient, pushing the pusher with respect to the patient, or both. This creates relative motion between the needle and the pusher, thereby exteriorizing the device. During the exteriorization process the device assumes its expanded deployed state within the target.
In a preferred embodiment, the device may be used as a filtering device (hereinafter “filtering device” or “embolic protection device”) for cardio-embolic stroke prevention. Such devices may be implanted at both carotid arteries to protect the brain from emboli originating in the heart, aorta, or other proximal large vessels.
The deployed state of the stroke prevention filtering device, according to those disclosed embodiments, may have the shape of a helical spring roughly occupying a spherical shell, with straight short ends extending from each side of the helix at the in the direction of the helix's principal axis of symmetry. Anchors for securing the filtering device to the carotid walls may reside at both ends. The anchors may also be made radiopaque or echogenic to provide visibility. When deployed, the device resides in transverse orientation within carotid artery lumen, the two device ends pierce the artery walls, and both anchors reside externally to lumen.
In the undeployed state, the device according to some embodiments, including anchors, resides within the lumen of the needle. The distal anchor is connected to the distal end of the helical spring and resides at distal end of the needle. The proximal anchor may be connected to the proximal end of the helical spring and reside closer to the proximal end of the needle than to the distal end of the device. After deployment, the anchors may self-expand to their deployed state.
Implantation, according to some embodiments, comprises insertion of the needle with the preassembled filtering device through the skin of the neck and transversally bisecting the carotid artery. Subsequently, the needle is retracted and the filtering device is exteriorized by the pusher. The filtering device assumes its deployed shape and is anchored externally to the carotid wall at both ends.
Experience shows that when the device is exteriorized from the needle, its distal end, at times, may rotate, bend, or twist. Therefore, whenever the device is exteriorized after its distal end is anchored in the carotid wall, this tendency to rotate, bend, or twist creates torque on the anchor. Accordingly, such torque might damage the tissue surrounding the anchor. Alternatively, the anchor may remain motionless but torsion may accumulate in the monofilament component of the device, thereby preventing it from assuming the desired deployed helical shape: The windings of the helix may distort and cross over.
Thus, there is a need for a helical filtering device that can be inserted into the carotid arteries in a safe and reproducible manner.
There is also a need to provide a helical filtering device that can transition from a helical shape to a substantially linear shape and back, without plastically deforming.
There is also a need for a helical filtering device (or any other monofilament device) in which torsion does not accumulate during deployment.
There is also a need for a helical filtering device (or any other monofilament device) comprising at least one bearing.
There is also a need for a system and method for safe implantation of a monofilament helical filtering device (or any other monofilament device) such that damage to the vessel walls and surrounding tissues is avoided.
There is also a need to provide a system for automatically implanting a filtering device (or any other monofilament device) in a safe and reproducible manner.
There is also a need to provide a system for automatically implanting a filtering device (or any other monofilament device) using a single hand.
There is also a need to provide a system for implanting a filtering device (or any other monofilament device), the system including housing and a user interface.
There is also a need for a system for implanting a filtering device (or any other monofilament device), the system including one or more sensors. Sensors may provide an indication of the needle position within the body or an indication of the deployment status or progression.
There is also a need for a system for implanting a filtering device (or any other monofilament device) that prevents the build-up of torsion in the filtering device by synchronizing device exteriorization and device rotation, bending, or twisting.
There is also a need for a system for implanting a filtering device (or any other monofilament device) that prevents the build-up of torsion in the filtering device by synchronizing device exteriorization and device rotation, bending, or twisting, wherein the system comprises a power supply, a motor, a controller, a driving mechanism, a sensor, and a user interface.